1. Field of the Invention
The present invention relates to a dynamo-electric machine applicable to a motor and a generator and, more particularly, to a dynamo-electric machine that is directly coupled to a crankshaft of an internal combustion engine to be ideally used for starting the internal combustion engine and for generating power.
2. Description of the Related Art
As a dynamo-electric machine used for such a type of application, there is a claw pole synchronous motor disclosed in, for example, Japanese Patent No. 2641166.
FIG. 12 is a schematic configuration diagram showing the claw pole synchronous motor described in, for example, Japanese Patent No. 2641166.
Referring to FIG. 12, the conventional claw pole synchronous motor is configured using a flywheel 3 attached to a crankshaft 2 projecting from an end surface of an engine main body 1, and equipped with rotating field poles 4 provided on an outer peripheral portion of the flywheel 3, a field coil 5 disposed on an inner peripheral side thereof, and a starter coil 6 disposed on an outer peripheral side thereof. The rotating field poles 4 are provided integrally at regular intervals on the outer peripheral portion of the flywheel 3, and formed of first pole cores 7 having many claws 7a, second pole cores 8 having many claws 8a positioned between the claws 7a, and a nonmagnetic ring 9 coupling the first and second pole cores inside the distal ends of the claws 7a and 8a. The field coil 5 is constructed by winding a conductor around a field core 10 secured to the end surface of the engine main body 1 via a member (not shown) that shuts off a magnetic field, and housed in a recessed section 3a provided in the outer peripheral portion of the flywheel 3 such that its outer peripheral surface is close to and opposes the inner peripheral surface of the rotating magnetic pole 4. Very small gaps are provided between the opposing surfaces of the field core 10 and the flywheel 3 and between the opposing surfaces of the field coil 10 and the rotating field pole 4. The starter coil 6 is constructed by winding a conductor around an annular starter core 11 composed of many stacked steel plates, the inner surface thereof being close to and opposing the outer peripheral surface of the rotating field pole 4. Numerous slots 11a are formed at regular intervals in the inner periphery of the starter core 11. A three-phase coil is constructed by installing conductors in these slots 11a by three-phase distributed winding.
In the claw pole synchronous motor configured as described above, passing Direct currents through the field coil 5 generates a magnetic flux. The magnetic flux causes the claws 7a of the pole core 7 to be magnetized to the north polarity, and the claws 8a of the pole core 8 to be magnetized to the south polarity. Supplying a three-phase alternating current to the starter coil 6 causes a rotating magnetic field to be applied to the rotating field pole 4 to rotationally drive the flywheel 3, that is, the crankshaft 2, thereby starting the engine.
Stopping the supply of the three-phase alternating current to the starter coil 6 causes the rotating magnetic field formed by the rotating field pole 4 to be applied to the starter coil 6 instead. This generates induced electromotive force in the starter coil 6, so that the motor acts as a generator.
As another dynamo-electric machine used for such a type of applications, there is an inductor type generator disclosed in, for example, Japanese Examined Patent Publication No. 2-43029.
FIG. 13 is a perspective view showing the inductor type generator disclosed in, for example, Japanese Examined Patent Publication No. 2-43029, and FIG. 14 is a development front view showing an essential section of the inductor type generator shown in FIG. 13.
The conventional inductor type generator shown in FIG. 13 and FIG. 14 has many inductor magnetic poles 15 provided at predetermined pitches in a circumferential direction on the outer peripheral surface of a flywheel 14 attached to a crankshaft 13 directly coupled to an engine. The flywheel 14 provided with the inductor magnetic poles 15 constitutes a rotor. The starter 16 is equipped with a plurality of pole cores 17 arranged in the circumferential direction of the flywheel 14. Bottom ends of pole cores 17 face against the inductor magnetic poles 15 with small gaps provided therebetween, while top ends thereof are secured to a cover plate 19a of a case 19 via a stator yoke 18. Each armature coil 20 is wound around two pole cores 17, while each excitation coil 21 is wound around each of the pole cores 17.
In the inductor generator configured as described above, passing Direct currents through the excitation coils 21 causes the excitation coils 21 to be energized. The excitation coils 21 cause the pole cores 17, two each, to be magnetized so that they are magnetized in the opposite directions to each other, and paired pole cores 17 wrapped with the same armature coil 20 are magnetized to have opposite polarities to one another. Accordingly, at a certain moment, a magnetic circuit 22 indicated by a dashed line in FIG. 14 is created, and when the flywheel 14 rotates to cause the inductor magnetic poles 15 to move for an angle corresponding to the pitch of the pole cores 17, a magnetic circuit 23 indicated by a chain line in FIG. 14 is formed. A magnetic flux passing through these magnetic circuits 22 and 23 is interlinked with the armature coils 20, and the direction of the magnetic flux passing through the magnetic circuit 22 is opposite to the direction of the magnetic flux passing through the magnetic circuit 23. Changes in the magnetic fluxes induce electromotive forces in the armature coils 20, causing the motor to act as a generator.
On the other hand, in this conventional inductor generator, the excitation coils 21 are energized by a battery (not shown) to form the magnetic circuits 22 and 23 alternately. At the same time, currents that reverse the directions thereof alternately pass through the armature coils 20 disposed to be interlinked with the magnetic circuits 22 and 23 as the flywheel 14 rotates or the inductor magnetic poles 15 rotate. This causes the armature coils 20 to be subjected to torque in a rotational direction. The armature coils 20 make up a stator, so that it cannot rotate; the inductor magnetic poles 15 are subjected to a reactive force thereof. Thus, the flywheel 14 provided with the inductor poles 15 rotates to provide the motor for starting the engine.
The rotating field pole 4 serving as the rotor of the conventional claw pole synchronous motor is constructed by the first pole cores 7 having many claws 7a, second pole cores 8 having many claws 8a positioned between the claws 7a, and the nonmagnetic ring 9 coupling the two types of pole cores inside the distal ends of the claws 7a and 8a. Hence, the rotor has the complicated structure, presenting a problem in that it exhibits unsatisfactory strength against a centrifugal force during high-speed revolution, leading to a possibility of damage to the rotor during a high-speed operation.
Furthermore, in the conventional inductor generator, each of the armature coils 20 wraps two pole cores 17. This requires a longer coil with consequent higher coil resistance, meaning an increased copper loss when currents pass through the armature coils 20, with resultant deteriorated efficiency.
The present invention has been made with a view toward solving the problems described above, and it is an object of the present invention to provide a dynamo-electric machine that acts as a motor and a generator, features higher strength against a centrifugal force during high-speed revolution so as to protect a rotor from damage during the high-speed revolution, and also features lower coil resistance of armature coils to suppress deterioration of efficiency caused by copper loss.
In order to achieve the above object, according to one aspect of the present invention, there is provided a dynamo-electric machine including: a stator having an iron core constructed by linking outer peripheral portions of a plurality of teeth arranged at equiangular pitches in a circumferential direction by an annular core back, and a plurality of coils wound around the teeth; and a rotor constructed by a plurality of magnetic poles composed of magnetic members arranged at equiangular pitches in the circumferential direction, the magnetic poles being formed into one piece by a base portion composed of a nonmagnetic member, and the rotor being rotatably disposed around an axis of the stator and adjacently to an inner periphery of the stator, wherein the plurality of coils are composed of a plurality of first coils that are excited by alternating current and a plurality of second coils that are excited by direct current, each of the coils being wound around each of the teeth without involving any other teeth.